Question 976063
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The other tutor didn't use the substitution method but used the 
addition (elimination) method.  Even though it's easier here, one
must follow instructions.  Here's the substitution method:
</pre>
solve the equation by the use of substitution method showing all the steps taken
in solving equation;
<pre>
{{{system(expr(2/5)x + expr(3/2)y = 2,
expr(7/3)x - expr(5/4)y = -5)}}}

Get rid of the fractions first by muyltiplying the first equation
through by the LCD of 10 and the second one through by the LCD of 12

{{{system(4x+15y=20,28x-15y=-60)}}}

Solve the first equation for 4x = 20-15y

Then since 28x is 7*4x, replace 28x by 7(20-15y) in the second equation:

      28x-15y = -60
7(20-15y)-15y = -60
 140-105y-15y = -60
     140-120y = -60
        -120y = -200
            y = 5/3

Substitute in 

           4x = 20-15y
           4x = 20-15(5/3)
           4x = 20-25
           4x = -5
            x = -5/4

Edwin</pre>